1. Technical Field
The present disclosure relates to a surgical trocar assembly and, in particular, to a trocar assembly having an integral latch mechanism which locks a protective shield of the trocar assembly in a fixed position and prevents retraction within the housing to the trocar assembly. Subject matter related to this application is disclosed in commonly assigned U.S. patent application Ser. No. 09/526,837 filed Mar. 16, 2000, entitled “Modular Trocar System and Methods of Assembly”, and U.S. application Ser. No. 5,352,274 entitled “SAFETY TROCAR”, filed Dec. 7, 1994 by Green, now U.S. Pat. No. 5,486,190, the contents of which are incorporated herein by reference.
2. Background of Related Art
Trocars are sharp pointed instruments used to puncture a body cavity. Generally, a trocar includes an obturator having a sharp obturator lip for penetrating the cavity wall and a protective sleeve in which the obturator is coaxially positioned. The trocar further includes a trocar sleeve or cannula. Once the body cavity has been punctured by the trocar, the obturator is typically removed from the cannula, thereby leaving the cannula in place extending into the body cavity. Endoscopic or laparoscopic procedures are then performed with surgical instruments, e.g., laparoscopes, dissectors, graspers, staplers introduced through the cannula.
Commercially available safety trocars includes a spring loaded safety shield which is adapted to cover the obturator tip once the body cavity has been entered so as to provide an increased level of protection to internal structures from puncture or laceration. Other available safety trocars incorporate latching mechanisms having complex trigger and linking arrangement for locking and unlocking the protective sleeve. For example, a convenient location of the trigger on the trocar may require at least one intermediary linking mechanism to operatively connect the trigger with the locking member. The intermediary linking mechanism moves the locking member for the locking or unlocking of the shield in response to an operator's movement of the trigger. Latch mechanisms also generally require multiple bias members to ensure the positioning and the desired interrelation of the components such as the blocking member and linking mechanism. These configurations often require tightly controlled tolerances and are complex and time consuming to assemble. Additional complications include the manual adjusting of the interrelated components, such as the biased elements, after manufacturing in order to ensure the desired operational quality and reliability of the device.
A continuing need exists for a trocar latch mechanism that is monolithically molded as an assembly requiring a minimal number or even no additional components. A continuing need also exists for a trocar latch mechanism that reduces manufacturing costs by minimizing the need for manual post manufacturing adjusting of the latch mechanism.